key: cord-313215-diqfmitr
authors: Luo, Lei; Liu, Dan; Zhang, Hao; Li, Zhihao; Zhen, Ruonan; Zhang, Xiru; Xie, Huaping; Song, Weiqi; Liu, Jie; Huang, Qingmei; Liu, Jingwen; Yang, Xingfen; Chen, Zongqiu; Mao, Chen
title: Air and surface contamination in non-health care settings among 641 environmental specimens of 39 COVID-19 cases
date: 2020-07-09
journal: bioRxiv
DOI: 10.1101/2020.07.09.195008
sha: 
doc_id: 313215
cord_uid: diqfmitr

Background Little is known about the SARS-CoV-2 contamination of environmental surfaces and air in non-health care settings among COVID-19 cases. Methods and findings We explored the SARS-CoV-2 contamination of environmental surfaces and air by collecting air and swabbing environmental surfaces among 39 COVID-19 cases in Guangzhou, China. The specimens were tested by RT-PCR testing. The information collected for COVID-19 cases included basic demographic, clinical severity, onset of symptoms, radiological testing, laboratory testing and hospital admission. A total of 641 environmental surfaces and air specimens were collected among 39 COVID-19 cases before disinfection. Among them, 20 specimens (20/641, 3.1%) were tested positive from 9 COVID-19 cases (9/39, 23.1%), with 5 (5/101, 5.0%) positive specimens from 3 asymptomatic cases, 5 (5/220, 2.3%) from 3 mild cases, and 10 (10/374, 2.7%) from 3 moderate cases. All positive specimens were collected within 3 days after diagnosis, and 10 (10/42, 23.8%) were found in toilet (5 on toilet bowl, 4 on sink/faucet/shower, 1 on floor drain), 4 (4/21, 19.0%) in anteroom (2 on water dispenser/cup/bottle, 1 on chair/table, 1 on TV remote), 1 (1/8, 12.5%) in kitchen (1 on dining-table), 1 (1/18, 5.6%) in bedroom (1 on bed/sheet pillow/bedside table), 1 (1/5, 20.0%) in car (1 on steering wheel/seat/handlebar) and 3 (3/20, 21.4%) on door knobs. Air specimens in room (0/10, 0.0%) and car (0/1, 0.0%) were all negative. Conclusions SARS-CoV-2 was found on environmental surfaces especially in toilet, and could survive for several days. We provided evidence of potential for SARS-CoV-2 transmission through contamination of environmental surfaces.

The Coronavirus Disease 2019 pandemic has precipitated a global crisis, 47 and it has resulted in 5404512 confirmed cases including with 343514 deaths globally 48 as of May 26, 2020 [1] . Reported transmission modes of Severe Acute Respiratory 49 Syndrome Coronavirus 2 (SARS-CoV-2) among humans mainly through respiratory 50 droplets produced when an infected case sneezes or coughs [2] . People may be infected 51 by inhalation of virus laden liquid droplets, and infection is more likely when someone 52 are in close contact with COVID-19 cases [2] [3] [4] . However, the importance of indirect 53 contact transmission, such as environmental contamination, is uncertain [5] [6] [7] . 54 Evidences suggested that environmental contamination with SARS-CoV-2 is likely to 55 be high, and it is supported by recent researches focus on environmental contamination 56 from COVID-19 cases in hospital [5] [6] [7] [8] . Hospitals already have perfect disinfection 57 measures and are less likely to appear super-spreaders compared with community and 58 family [4, [9] [10] [11] . However, the role of air and surface contamination in non-health care 59 settings is still need to be explored. Therefore, it is vital to understand the environmental 60 contamination of infected cases by SARS-CoV-2 in non-health care settings, which was 61 a vital aspect of controlling the spread of the epidemic.

To address this question, in this study, we sampled total of 641 surfaces 63 environmental and air specimens among 39 cases in Guangzhou, China, to explore the 64 surrounding environmental surfaces and air contamination by SARS-CoV-2 in non-65 health care settings.

Study design and setting 68 Based on COVID-19 case reports from Jan 27 to Apr 9, 2020, environmental surfaces 5 69 and air specimens were collected by Guangzhou CDC (GZCDC) from Feb 6 to Apr 10, 70 2020. The environmental surfaces specimens of COVID-19 cases sampled in home, 71 hotel, public area, restaurant, marketplace, car and pet, which was associated with 72 COVID-19 cases' life trajectory before hospitalization. Air specimens of cases also sampled in their room (home or hotel). Based on cases' reported activity 74 tracks, the number of specimens collected per COVID-19 case varied. All specimens 75 were collected before disinfection. handlebar) were also mixed form.

Air specimens was sampled using an MD8 microbiological sampler (Sartorius, 108 Germany) and sterile gelatin filters (3 µm pores and 80 mm diameter, Sartorius, 109 Germany) [7, 14] . Air specimens was sampled for 10 minutes in toilet, anteroom and The asymptomatic persons infected with SARA-CoV-2 (asymptomatic cases in short) 124 refers to those who have no relevant clinical manifestations including clinically 125 detectable signs or self-perceived symptoms such as fever, cough, or sore throat, but (Table 1) .

Distribution of environmental specimens among 39 COVID-19 cases. A total of 641 157 environmental surfaces and air specimens were collected among 39 COVID-19 cases, 158 and 20 specimens (20/641, 3.1%) were positive by RT-PCR testing from 9 COVID-19 159 cases (9/39, 23.1%), with 5 (5/101, 5.0%) positive specimens from 3 asymptomatic 160 cases, 5 (5/220, 2.3%) from 3 mild cases, and 10 (10/374, 2.7%) from 3 moderate cases 161 ( of SARS-CoV-2 (Table 2) . 166 All the 20 positive specimens were collected within 3 days (≤3 days) from diagnosis 167 to sampling (Figure 1 ), and 13 (13/259, 5.0%) positive environmental surfaces 168 specimens were collected from home, 6 (6/113, 5.3%) from hotel and 1 (1/5, 20.0%) 169 from car that had driven. While, specimens in restaurant that had eaten (0/30, 0.0%), 170 marketplace that had visited (0/122, 0.0%), pet that had lived with (0/4, 0.0%) and 171 public area that had stayed (0/108, 0.0%) were all negative by RT-PCR testing (Table   172 2). Although, the RT-PCR testing among specimens in restaurant and marketplace was 210 negative, the huge number of people exposed to there also existed great risk. Previous suggesting sharing indoor space was a major risk of SARS-CoV-2 infection.

All environmental specimens were collected before they were diagnosed in our study, 216 which indicated that a person who exposed to environmental contamination from 217 COVID-19 cases had a high infected risk unknowingly. In addition, SARS-CoV-2 had 218 a great opportunity of surviving for a while on surfaces such as toilet, anteroom, and 219 kitchen in current study. Therefore, we suggested that home quarantine for suspected 220 COVID-19 cases might be not a good control strategy. It was difficult to ensure that 221 cluster infection did not occur in families during the quarantine period for at least 222 fourteen days because they shared areas like toilets during quarantine. Previous study 223 also suggested that home quarantine required personal protective equipment and 224 professional training, but for ordinary people and families, especially those living 225 together in a narrow space, was obviously hard to implement excellent infection control, 226 causing other families to be infected [11, 25, 26] and centralized quarantine was 227 recommended in this condition [27] .

Previous study showed that COVID-19 cases with severe disease had significantly 229 higher viral loads than that with mild disease in respiratory specimens [28] . We tried to 230 explore whether the more serious the COVID-19, the more contaminated to the 231 environment surfaces. In this study, 24 environmental surfaces specimens were 232 collected in marketplace from one severe COVID-19 cases, and the specimens' RT-233 PCR testing was negative, which was probably due to the sampling site was where he 234 or she came into contact occasionally. In other cases, several environmental surfaces 235 specimens were tested positive with 5 (5/32, 15.6%) for 3 asymptomatic cases, 5 (5/53, 236 9.4%) for 3 mild cases, 10 (10/51, 19.6%) for 3 moderate cases, suggesting all cases 237 would contaminate environmental surfaces. In addition, COVID-19 cases without 238 symptoms like fever, dry cough, expectoration, fatigue, myalgia, diarrhea, were more 12 239 likely to have positive specimens of SARS-CoV-2. It might due to that people with 240 symptoms were quarantined more quickly in general, while, people without symptoms 241 would continue to contaminated the environmental surfaces and air before they were 242 admitted to hospital. We highly recommend that persons no matter COVID-19 cases or Note: Environmental specimens were tested by RT-PCR testing; 5 positive environmental specimens of asymptomatic COVID-19 cases were excluded in bars of symptoms onset to sampling. Note: (+) represents positive environmental surfaces specimens, and (−) represents negative environmental surfaces and air specimens; the number represents the count of negative/positive environmental specimens; white blank represents without specimens.

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Severity of COVID-19 at the time of diagnosis

Ly%=lymphocyte percentage; Ne= neutrophilic granulocyte; Ne%= neutrophilic granulocyte percentage

b: data on May 10;c: Data at hospital admission; Number of participants with missing Values: c=6, d=8

Public area included elevator, elevator button, stair armrest. b: 9 asymptomatic COVID-19 cases with 101 environmental specimens were excluded. c: A total of 136 specimens were

COVID-19 cases who with at least one positive environmental specimen